Scientific Opinion on the substantiation of health claims related to
linoleic acid (LA) in combination with gamma-linolenic acid (GLA) and
reduction of ocular dryness (ID 4274) pursuant to Article 13(1) of
Regulation (EC) No 1924/2006[sup]1[/sup]
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3
European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe:
Linoleic acid
eye
gamma-linolenic acid
health claims
n-6 fatty acids
ocular dryness
1. Charakterystyka żywności / składnika
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Zmniejszenie suchości oka
The food constituent that is the subject of the health claim is linoleic acid (LA) in combination with gamma-linolenic acid (GLA).
LA (18:2, n-6) is present in various vegetable oils and legumes. In humans, LA is metabolised to GLA and arachidonic acid (ARA), which is further metabolised into eicosanoids of the 2-series. LA can be measured in foods by established methods.
GLA (18:3, n-6) is present in small amounts in a variety of foods of both plant and animal origin, and can also be synthesised in the human body from LA. It is found in relatively high abundance in the plant seed oils of evening primrose, blackcurrant and borage, and in fungal oil (Fan and Chapkin, 1998). GLA can be measured in foods by established methods.
The Panel considers that the food constituents, LA and GLA, which are the subject of the health claim, are sufficiently characterised.
2. Znaczenie oświadczenia dla zdrowia człowieka
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Zmniejszenie suchości oka
The claimed effect is “ocular comfort”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to the reduction of ocular dryness by promoting tear production.
The Panel considers that reduction of ocular dryness is a beneficial physiological effect.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka - Zmniejszenie suchości oka
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Zmniejszenie suchości oka
One double-blind, randomised, controlled clinical trial investigated the effect of oral n-6 polyunsaturated fatty acids (n-6 PUFAs) (28.5 mg LA and 15 mg GLA twice daily vs. placebo) on inflammation markers of the ocular surface (human leukocyte antigen DR (HLA-DR)), measures of
tear production and state of the ocular surface, and ocular dryness symptoms in 26 subjects with keratoconjunctivitis sicca (dry eyes) (Barabino et al., 2003). Patients with and without Sjögren’s syndrome were included. Another double-blind, randomised, controlled, clinical trial investigated the effect of oral n-6 PUFAs (112 mg LA and 15 mg GLA twice daily) vs. placebo on prostaglandin E1 (PGE1) tear content, measures of tear production and state of the ocular surface, and ocular dryness symptoms in 40 subjects with Sjögren's syndrome (Aragona et al., 2005). The Panel considers that the evidence provided does not establish that patients with Sjögren’s syndrome are representative of the general population with regard to the status of the lacrimal glands, or that results obtained in studies on patients with Sjögren’s syndrome can be extrapolated to the general population with regard to ocular dryness.
One double-blind, randomised, clinical trial in 60 subjects investigated the effect of oral n-6 PUFAs (28.5 mg LA and 15.1 mg GLA once daily) vs. no treatment on ocular comfort, measures of tear production, and state of the ocular surface following photorefractive keratectomy (PRK) (Macri et al., 2003). The Panel considers that the evidence provided does not establish that subjects undergoing photorefractive keratectomy are representative of the general population with regard to ocular hydration, or that results obtained in studies on subjects undergoing photorefractive keratectomy can be extrapolated to the general population with regard to ocular dryness.
The Panel notes that no references were provided from which conclusions could be drawn for the scientific substantiation of the claim.
The Panel concludes that a cause and effect relationship has not been established between the consumption of LA in combination with GLA and reduction of ocular dryness.
Wnioski
On the basis of the data presented, the Panel concludes that:
The food constituents, LA and GLA, which are the subject of the health claims, are sufficiently characterised.
The claimed effect is “ocular comfort”. The target population is assumed to be the general population. In the context of the proposed wordings, it is assumed that the claimed effect refers to the reduction of ocular dryness by promoting tear production. Reduction of ocular dryness is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of LA in combination with GLA and reduction of ocular dryness.